Study On Solid Powder Boronizing Process Of H13 Steel

Solid boronizing technology is a commonly used surface treatment method for improving the service life of H13 hot work die steel.The traditional boronizing treatment is carried out at high temperature,and the energy consumption is large,which can lead to the serious deformation of the workpiece.Boron-nickel co-infiltration and rare earth catalysis have become one of the leading research directions in this field.In this paper,H13 steel was used as the substrate to study the effect of the formulation on the microstructure of boronized layer.The effects of process conditions?boronizing temperature and holding time?on the microstructure and properties?hardness?of boron-nickel infiltration were studied.Effect of Rare Earth-Dewatering on Microstructure and Properties of Boronizing Layer.The experimental results are of great significance to optimize the boron-nickel permeation process and rare earth fertilization process of H13 steel.Experimental results show:?1?Under the condition of 860?×4h,the effect of boron carbide-potassium fluoroborate type boronizing agent on the microstructure and properties of H13 steel was studied by two-factor method.The optimum boronizing agent ratio was: 5%B4C + 5%KBF4 + 5%C + balance SiC,the infiltration material presents boronizing layer,transition layer and matrix three layers.The boronizing layer is Fe B + Fe 2B biphasic structure with Fe₂ B phase,Thickness between 10¹4?m,boride surface hardness value of 1100¹350HV0.1.?2?The surface of the material was nickel-plated.After 920?×4h diffusion annealing and boron-nickel co-infiltration,the boron-nickel permeation process parameters were optimized at 980?×5h,the thickness of the infiltration layer was about 112.75?m,it is Single boron infiltration layer thickness of 2 times.?3??Fe,Ni?phase,Ni₂B phase,Fe₂ B phase and ?-?Fe,Ni?phase.The formation of ?-?Fe,Ni?solid solution,the hardness and brittleness of the nickel-boron infiltration layer are less than that of the single boron layer.?4?Under the condition of 980?×5h,the hardness gradient curve shows similar characteristics compared with boronizing and Ni-boronizing.Compared with the depth of boronizing layer,the hardness value of the infiltration layer is also increased.The maximum hardness of ordinary boron is between 25?m and the maximum hardness is up to 1550HV0.1,and the maximum value of nickel plating boron hardness appears at 27?m,1420HV0.1.?5?The boronizing temperature significantly affects the thickness of boronizing layer.With the increase of temperature,the boron thickness increases with the increase of temperature,and the optimum temperature is 980?,and the suitable holding time is 5h.CeO₂ rare earth is 2%,the thickness of the infiltration layer is 85.77?m,the thickness of boron is 19.95?m,the best addition of La₂O₃ is 1.4%,the thickness of the layer is 76.519?m,Thick increase of 10.24?m.?6?The hardness of CeO₂ rare earth is about 1210HV0.1,the hardness is reduced by 340HV0.1 compared with the hardness of single boron oxide at 980?×5h.The addition of La₂O₃ rare earth The hardness is about 1430HV0.1,the hardness value is reduced by 120HV0.1.Which effectively reduces the hardness gradient of the boronizing layer in the ordinary boronizing experiment,strengthens the bonding force between the boronizing layer and the matrix,and improves the wear resistance and impact resistance.?7?The thickness of boronized layer of nickel-boron permeated sample is larger than that of rare earth-boron infiltration experiment.The effect of adding rare earth on the hardness gradient of boronizing layer and matrix is stronger than that of boron-nickel Infiltration H13 steel is more sensitive to CeO₂ rare earth,adding CeO₂ rare earth than adding La₂O₃ rare earth is more likely to promote the formation of Fe₂ B phase,the catalytic effect is better than La₂O₃ rare earth.